This invention relates to apparatus for handling disk recording media and in particular to novel improved methods and apparatus for handling packaged "disk packs".
Workers in the data recording arts are familiar with disk recording media and associated record handling equipment. Such equipment has found wide-spread favor, for instance, as related to "flexible" (or "floppy") disks, but heretofore will be recognized as adapted to handle only single-disk cartridges, as opposed to multi-disk media, (such as a stacked array of floppy disks). The present invention is intended to provide improved disk handling equipment adapted to handle such multi-disk media.
Workers in this art will acknowledge the significant advantages accruing with the use of flexible disk media and associated handling equipment. Flexible disk records facilitate "random access" data processing, they facilitate "open-ended" data fields and provide a unit record that is compact and light, that is readily transported, stored and that may be handled interchangeably with other like disks. Thus, it is important, today to facilitate the efficient handling of floppy disks and the automatic processing of data recorded thereon. Accordingly the present invention is designed to improve flexible disk handling apparatus, making it more "cost effective" as well as to provide a multi-disk handling capability in equipment that is roughly interchangeable with, and compatible with, single-disk equipment.
The typical floppy magnetic disk will be recognized as comprising a thin planar sheet of circular configuration and comprising of polyester sheet material (e.g., the familiar polyethylene terephthalate used for magnetic recording tape), with a magnetic coating thereon and provided with a center hole to accommodate a rotary-drive spindle. Such a prior art floppy disk is depicted schematically in FIG. 1. Typically, a single-disk is packaged in a protective jacket, like that depicted, for example, in U.S. Pat. No. 3,864,755.
Workers in the art will recognize certain disk handling equipment adapted for processing such single-disk cartridges are presently available in the art. Workers will further recognize that, while it would be quite advantageous to adapt such conventional single-disk handling equipment to accommodate multi-disk cartridges, there are some rather foreboding problems that arise; for instance; how to partition (split) the disk pack and expose a selected disk (surface) for access by a transducer assembly; or how to open and spread the protective jacket to accommodate this -- not to mention the problem of how to do this while the disk pack is kept rotating within its jacket!
The present invention is designed to meet all these difficult problems, providing equipment designed to handle multi-disk cartridges, while nonetheless being functionally similar to conventional single-disk equipment. Workers will recognize that such functional interchangeability enhances the natural advantages of flexible disk media; i.e., such advantages as their ability to facilitate the exchange of data-set libraries, or to provide a ready data-backup for security purposes or to generally facilitate ready interchange of disk media between various processing terminals; for instance, thereby allowing computer records to be readily transported between various process stations, by mail and otherwise.
Workers will recognize that apparatus according to the invention co-opts certain features of conventional disk drives and advantageously adapts them to be used interchangeably with a broad spectrum of disks and disk apparatus. The present invention is directed, according to one feature, to solving the problem of so adapting a conventional disk drive design to accommodate multi-disk cartridges -- preferably while nonetheless retaining interchangeability with single-disk cartridges and with related handling apparatus.
In accordance with the invention, it has been found that floppy disks may be stacked and assembled into disk packs, as well as retained within a prescribed multidisk jacket to form a cartridge which may be processed like the "single-disk disk" cartridge -- this resulting in obvious benefits and advantages. Workers will recognize that such a multi-disk unit record is new and particularly advantageous in several respects -- for instance, it greatly enhances the volumetric efficiency of data storage, (maximizing the number of data bits packed into a prescribed medium volume, the disks being so thin and compliant as to intimately pack together); yet it is quite tolerant of ordinary handling stresses and of common storage environments, and avoids serious compromise to data integrity. The present invention is especially adapted for providing methods and associated means for so handling such multi-disk cartridges. --the special problems of flexible disks:
Workers are well aware of the special advantages to using floppy disk media -- such advantages as: increased bit density and cost effectiveness (e.g., stemming from increases in disk area density and capacity per disk spindle); an increase in "data-rates" and associated reduction in access motion and/or in rotational delay; also improved reliability and data handling performance, along with reducing cost per Mega-byte stored.
Workers will also readily recognize how useful a pack of such floppy disks could prove to be. But they can also perceive how particularly difficult it is to provide associated "floppy pack" processing equipment; e.g., which is adapted to automatically open and spread a cartridge jacket to automatically partition the stack of disks, and to give satisfactory access to a transducer assembly, etc. The present invention is adapted to accomplish these objectives with automatic equipment which is relatively simple, yet cost-effective, while presenting no danger of damaging or defacing the recording characteristics of the plastic disk sheets. With such disk packs packaged as mentioned in protective jackets as a multi-disk cartridge, the invention is designed to provide an associated disk file apparatus facilitating the aforementioned functions of jacket-opening, pack-partitioning and transducer-access.
However, workers in this art have heretofore contemplated that the handling of floppy disks presented certain problems requiring "extreme measures." Some have expected it would be necessary to house such disks in a relatively rigid containment structure. Others have postulated complex suspension structures. Some have despaired of finding any simple, practical means of accessing individual selected recording surfaces in a "floppy disk pack" in the precise, rapid, repeatable manner that is typically required -- this principally because a floppy substrate seemed so difficult to hold in position and stabilize -- and it is not surprising that workers have anticipated tremendous difficulties in precisely positioning a Read/Write head between two tissue-thin floppy disks, separated by no more than a few mils, let alone doing so quickly and simply. Also, these flexible records present problems of dimensional instability and variations, such as from their varying responses to thermal effects and from discrepancies in manufacturing tolerances.
Thus, even if one could reasonably expect to position each floppy disk in a stack at a constant reference position relative to the other disks, the prospect of quickly and accurately "finding" a "selected" one of the disks and contacting it with a transducer assembly, has seemed dismal. Accordingly it was surprising to discover a comparatively simple, convenient, and inexpensive means of manipulating such floppy disk packs to afford transducer access according to the invention.
Now, workers dealing with flexible media have resorted to special means for packaging the disk as well as for accessing it. A floppy disk was presumed to require extensive support while rotated for transducing purposes; further, since it was assumed that floppy disks would be unacceptably impaired by surface friction when placed in direct contact, workers have avoided stacking them one upon the other. Using methods and associated means according to the invention, it has been found that flexible disks may indeed be so stacked directly upon one another, yet still be manipulated, relatively simply and conventionally, for transducer access -- all this without compromising such characteristic "floppy disk advantages," as compactness, ready transportability, low cost, etc.
With increased use such flexible disk media the "removability" and "interchangeability" of associated unit records has become increasingly important. Workers are aware that the disks which are readily removed and exchanged afford greater flexibility and versatility in use as compared with a fixed-installation disk, or disk pack -- e.g., the recorded data may be stored "off-line" and read-out later on call. Also interchangeable disks may be used interchangeably in any number of drive units (of the same type) and be transferred (e.g., mailed) from one terminal to another. Such removability and mobility of flexible disk media has its price, however, for instance, it typically requires disk-loading hardware, disk packaging means (insuring protection against contamination and for security of data); and positioning means (for the accurate, repeatable transducer carriage to any disk) with associated control electronics (e.g., arranged to reliably and repeatably "find" any prescribed track on any floppy disk injected into the machine). The present invention is directed toward providing equipment for so handling an integral flexible disk pack in a manner that meets the cited problems and objectives, while still satisfying countervailing objectives of reasonable cost relative convenience and simplicity of implementation and the like.
Various known forms of flexible disk media and associated packaging and handling means are described in the above cited copending Applications. Workers will recognize that one of the principle difficulties that arise when one deals with a "floppy disk" is its vulnerability to defacement. The typical thin compliant plastic disk appears relatively fragile and rather susceptible to damage by some fairly common physical hazards -- such as rupture by impact or sliding contact with a head carriage, with a "separator knife," or with an access-arm on a disk handling assembly, or by other sharp edges. This invention accomplishes its objectives using none of such prior art techniques.
Now, while the cost of the disk (cartridge) is relatively inconsequential, the value of the data stored thereon may be tremendous -- such that if the recording surface is so defaced or destroyed by such contact that data is lost, the efficiency and security of an entire associated data processing system may be seriously impaired. The present invention is designed to facilitate the use of such multi-disk flexible media, while yet handling it safely and alleviating, or eliminating, such risks to data integrity. A further object is to effect this by methods, and associated means, which are nonetheless simple, convenient and readily available. Yet a further object is to accomplish this with methods and means that are nonetheless practically interchangeable with those used for conventional single-disk handling equipment.
One problem will always come to mind when one contemplates data transfer with a stack of "floppy disks" -- how to separate them for transducer access?
Some general prior art approaches to the problem of access to a stack of recording disks may be gleaned from consideration of U.S. Pat. No. 3,509,533 to Krijnan and U.S. Pat. No. 3,618,055 to Van Acker; these involving disk separation by pneumatic means involving conduit which admit pressurized gas through a slotted spindle -- an approach more complicated than most workers care to even consider.
Similar prior art arrangements for handling flexible disks may be seen in U.S. Pat. Nos.: 3,153,241; 3,225,338; 3,369,227 and 3,573,771; with U.S. Pat. Nos. 3,678,481 and 3,815,150 indicating related data handling equipment. Other prior art arrangements for partitioning, a multi-disk stack while it is kept rotating, to afford clearance for entry and manipulation of a transducer assembly may be seen in U.S. Pat. No. 3,130,393 to Gutterman (employing pressurized gas to slide disks apart in a "forced piston" motion, something not really practical for flexible disk media); and in U.S. Pat. No. 2,960,340 to Seidel (involving injection of a probe between stacked phonograph records).
The present invention is designed to provide improved handling equipment with associated partitioning means which is simple, yet especially adapted for a stack of disks.
Workers will recognize the availability of a single-disk drive in the art, such as illustrated in U.S. Pat. No. 3,815,150 or U.S. Pat. No. 4,012,791. Such a conventional unit is typically intended for handling computer programs or other data prerecorded on a flexible single-disk packaged in a flexible plastic jacket so as to form a cartridge. Such a cartridge will be understood as including a central "drive aperture" (for receipt of the rotary drive spindle) and a radial slot through which a magnetic transducer head can engage a disk's magnetic recording tracks. This disk drive is adapted for insertion of such a cartridge through an entry port or slot in the machine, with the flexible disk thereupon being clamped to the unit's spindle for "transducer rotation." A cartridge holder is pivotably mounted so as to be depressed from a normal distal "loading" position to an operating position whereat it is thrust adjacent the drive spindle to clamp the intermediate inserted disk on the spindle and engage it therewith for rotation. A simple camoperated linkage is typically provided for so depressing this disk holder and clamping the disk upon the spindle automatically. Accordingly, when the cartridge is inserted into this drive unit along appropriately provided guideways, it will not touch the spindle or transducer head; but the holder will thereupon be clamped down to engage the disk with the spindle.
Preferably, a prescribed disk-locating "expansion core" arrangement is also provided on the spindle and is adapted to center the disk thereon as the clamp means thrusts the spindle head into the disk's center hole. The associated clamp is typically made "free floating," permitting it to accept the rotation axis of the spindle even when it is misaligned with the clamp's axis. The disk's recording tracks may next be engaged with the transducer head.
Workers will recognize that such single-disk equipment would be expected to become relatively complicated when, and if, it is to be adapted for handling a pack of disks. The present invention is designed to meet this contingency in a surprising manner, providing disk handling equipment which is simple, yet generally compatible with present single-disk equipment and which will nonetheless accommodate flexible disk packs and associated jacket opening means and pack-partitioning means.
The present invention is, moreover, preferably and particularly designed to accommodate a pack of hole-encoded flexible disks, as well as the positioning manipulations associated therewith -- more specifically, to provide pack-partitioning plunger means, and disk selection and transducer access with automatic equipment.
The present invention overcomes the foregoing and other disadvantages of prior art structures and methods and provides the mentioned and other features and advantages according to a novel design.
The foregoing and other features, objects and advantages, according to the present invention will be more fully appreciated and become more apparent from consideration of the following description of preferred embodiments of the invention, taken in conjunction with the attached drawings wherein like reference symbols denote like parts.